Merge pull request #573 from anirudherabelly/master

added problems for Heap and Stack

Author: matthewsamuel95

Data Structures/Heap/RunningMedian/RunningMedian_V1.java

@@ -0,0 +1,80 @@
+/*
+Given an input stream of n integers the task is to insert integers to stream and 
+print the median of the new stream formed by each insertion of x to the stream.
+--------------------------------------------------------------------------------
+Example
+
+Flow in stream : 5, 15, 1, 3 
+5 goes to stream --> median 5 (5)
+15 goes to stream --> median 10 (5, 15)
+1 goes to stream --> median 5 (5, 15, 1)
+3 goes to stream --> median 4 (5, 15, 1, 3)
+
+Input:
+The first line of input contains an integer N denoting the no of elements of the stream. 
+Then the next N lines contains integer x denoting the no to be inserted to the stream.
+
+Output:
+For each element added to the stream print the floor of the new median in a new line.
+
+Constraints:
+1<=N<=10^5+7
+1<=x<=10^5+7
+
+Example:
+Input:
+4
+5
+15
+1 
+3
+Output:
+5
+10
+5
+4
+*/
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+class GFG
+ {
+	public static void main (String[] args)
+	 {
+	 //code
+	 Scanner sc=new Scanner(System.in);
+        int n=sc.nextInt();
+        PriorityQueue<Integer> maxHeap=new PriorityQueue<Integer>(
+            new Comparator<Integer> () {
+                public int compare(Integer a, Integer b) {
+                    return b - a;
+                }   
+            }    
+        );
+        PriorityQueue<Integer> minHeap=new PriorityQueue<Integer>();
+        int first=sc.nextInt();
+        int second=sc.nextInt();
+        if(first<second){
+            maxHeap.add(first);
+            minHeap.add(second);
+        }
+        else{
+            maxHeap.add(second);
+            minHeap.add(first);
+        }
+        System.out.println(first);
+        System.out.println(((first+second))/2);
+        for(int i=0;i<n-2;i++){
+            int t=sc.nextInt();
+            if(t<maxHeap.peek())maxHeap.add(t);
+            else minHeap.add(t);
+            int diff=minHeap.size()-maxHeap.size();
+            if(diff>1)maxHeap.add(minHeap.poll());
+            if(diff<-1)minHeap.add(maxHeap.poll());
+            diff=minHeap.size()-maxHeap.size();
+            if(diff==0)System.out.println((minHeap.peek()+maxHeap.peek())/2);
+            else if(diff==1)System.out.println(minHeap.peek());
+            else System.out.println(maxHeap.peek());
+        }
+	 }
+}

Data Structures/Heap/RunningMedian/RunningMedian_V2.java

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+class MedianFinder {
+    
+    /** initialize your data structure here. */
+    PriorityQueue<Integer> minHeap = new PriorityQueue<Integer>();
+    PriorityQueue<Integer> maxHeap = new PriorityQueue<Integer>(
+        new Comparator<Integer>(){
+            public int compare(Integer a, Integer b){
+                if(a > b)return -1;
+                else if(a == b)return 0;
+                return 1;
+            }
+        }
+    );
+    
+    public MedianFinder() {
+        
+    }
+    
+    public void addNum(int num) {
+        int diff = maxHeap.size()-minHeap.size();
+        if(diff == 0){
+            minHeap.add(num);
+            maxHeap.add(minHeap.poll());    
+        }
+        else{
+            maxHeap.add(num);
+            minHeap.add(maxHeap.poll());    
+        }
+    }
+    
+    public double findMedian() {
+        double median = 0; 
+        int diff = maxHeap.size()-minHeap.size();
+        
+        if(diff==0)median = (maxHeap.peek()+minHeap.peek())/2.0;
+        else median = maxHeap.peek();
+        return median;
+    }
+}
+
+/**
+ * Your MedianFinder object will be instantiated and called as such:
+ * MedianFinder obj = new MedianFinder();
+ * obj.addNum(num);
+ * double param_2 = obj.findMedian();
+ */

Data Structures/Stack/BalancedParanthesis/BalancedParanthesis.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+class Solution {
+
+    static void Main(String[] args) {
+        int t = Convert.ToInt32(Console.ReadLine());
+        for(int a0 = 0; a0 < t; a0++){
+            string s = Console.ReadLine();
+            Console.WriteLine(CheckBalanced(s));
+        }
+    }
+    static string CheckBalanced(string s){
+        Stack<char> st=new Stack<char>();
+        foreach(char c in s){
+            if(c=='[' || c=='{' || c=='(')st.Push(c);
+            else{
+                if(st.Count==0)return "NO";
+                char ch=st.Pop();
+                if((ch=='(' && c==')')||(ch=='[' && c==']')||(ch=='{' && c=='}'))continue;
+                else return "NO";
+            }
+        }
+        if(st.Count!=0)return "NO";
+        return "YES";
+    }
+}

Data Structures/Stack/MaxHistogramArea/MaxHistogramArea.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+class Solution {
+    static void Main(String[] args) {
+        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
+        int n = int.Parse(Console.ReadLine());
+        int[] array = Array.ConvertAll(Console.ReadLine().Split(' '),int.Parse);
+        LargestRectangle(array,n);
+    }
+    private static void LargestRectangle(int[] array, int n)
+    {
+        Stack<int> st = new Stack<int>();
+        int i = 0,max_area=-1,area=0;
+        while (i < n)
+        {
+            if (st.Count == 0 || array[st.Peek()] <= array[i])
+            {
+                st.Push(i);
+                i++;
+            }
+            else
+            {
+                int top = array[st.Pop()];
+                area = top* ((st.Count == 0) ? i : i-st.Peek()-1);
+                if (area > max_area) max_area = area;
+            }
+        }
+        while (st.Count != 0)
+        {
+            int top = array[st.Pop()];
+            area = top * ((st.Count == 0) ? i : i - st.Peek() - 1);
+            if (area > max_area) max_area = area;
+        }
+        Console.WriteLine(max_area);
+    }
+}

Data Structures/Stack/MinStack/MinStack.java

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+class MinStack {
+    private class Node{
+        int val, min;
+        Node next;
+        Node(int val, int min, Node next){
+            this.val = val;
+            this.min = min;
+            this.next = next;
+        }
+    }
+    private Node head;
+    
+    /** initialize your data structure here. */
+    public MinStack() {
+        head = null;
+    }
+    
+    public void push(int x) {
+        if(head == null){
+            head = new Node(x, x, null);
+        }
+        else{
+            head = new Node(x, Math.min(x, head.min), head);
+        }
+    }
+    
+    public void pop() {
+        head = head.next;
+    }
+    
+    public int top() {
+        return head.val;
+    }
+    
+    public int getMin() {
+        return head.min;
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * MinStack obj = new MinStack();
+ * obj.push(x);
+ * obj.pop();
+ * int param_3 = obj.top();
+ * int param_4 = obj.getMin();
+ */